Turbine rotor modernization and repair method

Abstract

This invention relates to an improved method for repairing damaged or worn surfaces of turbine components or upgrading older designs to new, improved designs. This improved method applies to both high pressure and low pressure turbine components applications. This method includes depositing a plurality of individual spaced apart weld volumes onto a prepared surface of a turbine rotor. These individual spaced apart weld volumes form individual fingers without the need to machine the individual fingers from a single rectangular weld volume. Multiple weld volumes are formed concurrently with a space maintain between each weld volume using multiple torches without the problems normally associated with closely spaced welding arcs. Each individual spaced apart weld volume is formed by a plurality of layers of weld metal, with each layer being formed from a single oscillating weld bead to form a predetermined width. The filler wire may be heated by applying a current through the filler wire before it is fed into the weld pool. Welding parameters are also changed to increase the amount of weld deposition without adversely affecting the mechanical weld properties. The invention provides for reduced cycle time for repair work by using multiple torches simultaneously without causing arc instability. The invention also reduces cycle time, by eliminating the need of machining individual fingers on control stages from a single weld volume, by changing the weld buildup of multiple projections, slightly larger than the fingers which hold the blades.